4 ### Build a CDB file from configuration file
6 ### (c) 2007 Straylight/Edgeware
9 ###----- Licensing notice ---------------------------------------------------
11 ### This file is part of Trivial IP Encryption (TrIPE).
13 ### TrIPE is free software: you can redistribute it and/or modify it under
14 ### the terms of the GNU General Public License as published by the Free
15 ### Software Foundation; either version 3 of the License, or (at your
16 ### option) any later version.
18 ### TrIPE is distributed in the hope that it will be useful, but WITHOUT
19 ### ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
20 ### FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
23 ### You should have received a copy of the GNU General Public License
24 ### along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
28 ###--------------------------------------------------------------------------
29 ### External dependencies.
32 from optparse import OptionParser
34 from sys import stdin, stdout, exit, argv
37 from cStringIO import StringIO
39 ###--------------------------------------------------------------------------
42 class CDBFake (object):
43 """Like cdbmake, but just outputs data suitable for cdb-map."""
44 def __init__(me, file = stdout):
46 def add(me, key, value):
47 me.file.write('%s:%s\n' % (key, value))
51 ###--------------------------------------------------------------------------
52 ### A bulk DNS resolver.
54 class BulkResolver (object):
56 Resolve a number of DNS names in parallel.
58 The BulkResovler resolves a number of hostnames in parallel. Using it
59 works in three phases:
61 1. You call prepare(HOSTNAME) a number of times, to feed in the hostnames
64 2. You call run() to actually drive the resolver.
66 3. You call lookup(HOSTNAME) to get the address you wanted. This will
67 fail with KeyError if the resolver couldn't resolve the HOSTNAME.
71 """Initialize the resolver."""
75 def prepare(me, host):
76 """Prime the resolver to resolve the name HOST."""
77 if host not in me._resolvers:
78 me._resolvers[host] = M.SelResolveByName \
80 lambda name, alias, addr:
81 me._resolved(host, addr[0]),
82 lambda: me._resolved(host, None))
85 """Run the background DNS resolver until it's finished."""
91 Fetch the address corresponding to HOST.
93 addr = me._namemap[host]
98 def _resolved(me, host, addr):
99 """Callback function: remember that ADDR is the address for HOST."""
100 me._namemap[host] = addr
101 del me._resolvers[host]
103 ###--------------------------------------------------------------------------
104 ### The configuration parser.
106 ## Match a comment or empty line.
107 RX_COMMENT = RX.compile(r'(?x) ^ \s* (?: $ | [;#])')
109 ## Match a section group header.
110 RX_GRPHDR = RX.compile(r'(?x) ^ \s* \[ (.*) \] \s* $')
112 ## Match an assignment line.
113 RX_ASSGN = RX.compile(r'''(?x) ^
114 ([^\s:=] (?: [^:=]* [^\s:=])?)
119 ## Match a continuation line.
120 RX_CONT = RX.compile(r'''(?x) ^ \s+
124 ## Match a $(VAR) configuration variable reference; group 1 is the VAR.
125 RX_REF = RX.compile(r'(?x) \$ \( ([^)]+) \)')
127 ## Match a $[HOST] name resolution reference; group 1 is the HOST.
128 RX_RESOLVE = RX.compile(r'(?x) \$ \[ ([^]]+) \]')
130 class ConfigSyntaxError (Exception):
131 def __init__(me, fname, lno, msg):
136 return '%s:%d: %s' % (me.fname, me.lno, me.msg)
139 return ' -> '.join(["`%s'" % hop for hop in path])
141 class AmbiguousOptionError (Exception):
142 def __init__(me, key, patha, vala, pathb, valb):
144 me.patha, me.vala = patha, vala
145 me.pathb, me.valb = pathb, valb
147 return "Ambiguous answer resolving key `%s': " \
148 "path %s yields `%s' but %s yields `%s'" % \
149 (me.key, _fmt_path(me.patha), me.vala, _fmt_path(me.pathb), me.valb)
151 class InheritanceCycleError (Exception):
152 def __init__(me, key, path):
156 return "Found a cycle %s looking up key `%s'" % \
157 (_fmt_path(me.path), me.key)
159 class MissingSectionException (Exception):
160 def __init__(me, sec):
163 return "Section `%s' not found" % (me.sec)
165 class MissingKeyException (Exception):
166 def __init__(me, sec, key):
170 return "Key `%s' not found in section `%s'" % (me.key, me.sec)
172 class ConfigSection (object):
174 A section in a configuration parser.
176 This is where a lot of the nitty-gritty stuff actually happens. The
177 `MyConfigParser' knows a lot about the internals of this class, which saves
178 on building a complicated interface.
181 def __init__(me, name, cp):
182 """Initialize a new, empty section with a given NAME and parent CP."""
184 ## The cache maps item keys to entries, which consist of a pair of
185 ## objects. There are four possible states for a cache entry:
187 ## * missing -- there is no entry at all with this key, so we must
190 ## * None, None -- we are actively trying to resolve this key, so if we
191 ## encounter this state, we have found a cycle in the inheritance
194 ## * None, [] -- we know that this key isn't reachable through any of
197 ## * VALUE, PATH -- we know that the key resolves to VALUE, along the
198 ## PATH from us (exclusive) to the defining parent (inclusive).
204 def _expand(me, string, resolvep):
206 Expands $(...) and (optionally) $[...] placeholders in STRING.
208 RESOLVEP is a boolean switch: do we bother to tax the resolver or not?
209 This is turned off by MyConfigParser's resolve() method while it's
210 collecting hostnames to be resolved.
212 string = RX_REF.sub \
213 (lambda m: me.get(m.group(1), resolvep), string)
215 string = RX_RESOLVE.sub(lambda m: me._cp._resolver.lookup(m.group(1)),
220 """Yield this section's parents."""
221 try: names = me._itemmap['@inherit']
222 except KeyError: return
223 for name in names.replace(',', ' ').split():
224 yield me._cp.section(name)
226 def _get(me, key, path = None):
228 Low-level option-fetching method.
230 Fetch the value for the named KEY in this section, or maybe (recursively)
231 a section which it inherits from.
233 Returns a pair VALUE, PATH. The value is not expanded; nor do we check
234 for the special `name' key. The caller is expected to do these things.
235 Returns None if no value could be found.
238 ## If we weren't given a path, then we'd better make one.
239 if path is None: path = []
241 ## Extend the path to cover us, but remember to remove us again when
242 ## we've finished. If we need to pass the current path back upwards,
243 ## then remember to take a copy.
247 ## If we've been this way before on another pass through then return the
248 ## value we found then. If we're still thinking about it then we've
250 try: v, p = me._cache[key]
251 except KeyError: pass
253 if p is None: raise InheritanceCycleError(key, path[:])
254 else: return v, path + p
256 ## See whether the answer is ready waiting for us.
257 try: v = me._itemmap[key]
258 except KeyError: pass
261 me._cache[key] = v, []
264 ## Initially we have no idea.
268 ## Go through our parents and ask them what they think.
269 me._cache[key] = None, None
270 for p in me._parents():
272 ## See whether we get an answer. If not, keep on going.
273 v, pp = p._get(key, path)
274 if v is None: continue
276 ## If we got an answer, check that it matches any previous ones.
281 raise AmbiguousOptionError(key, winner, value, pp, v)
283 ## That's the best we could manage.
284 me._cache[key] = value, winner[len(path):]
288 ## Remove us from the path again.
291 def get(me, key, resolvep = True):
293 Retrieve the value of KEY from this section.
296 ## Special handling for the `name' key.
298 value = me._itemmap.get('name', me.name)
300 value, _ = me._get(key)
302 raise MissingKeyException(me.name, key)
304 ## Expand the value and return it.
305 return me._expand(value, resolvep)
307 def items(me, resolvep = True):
309 Yield a list of item names in the section.
312 ## Initialize for a depth-first walk of the inheritance graph.
317 ## Visit nodes, collecting their keys. Don't believe the values:
318 ## resolving inheritance is too hard to do like this.
321 if sec.name in visited: continue
322 visited[sec.name] = True
323 stack += sec._parents()
325 for key in sec._itemmap.iterkeys():
326 if key != '@inherit': d[key] = None
331 class MyConfigParser (object):
333 A more advanced configuration parser.
335 This has four major enhancements over the standard ConfigParser which are
338 * It recognizes `@inherits' keys and follows them when expanding a
341 * It recognizes `$(VAR)' references to configuration variables during
342 expansion and processes them correctly.
344 * It recognizes `$[HOST]' name-resolver requests and handles them
347 * Its parsing behaviour is well-defined.
351 1. Call parse(FILENAME) to slurp in the configuration data.
353 2. Call resolve() to collect the hostnames which need to be resolved and
354 actually do the name resolution.
356 3. Call sections() to get a list of the configuration sections, or
357 section(NAME) to find a named section.
359 4. Call get(ITEM) on a section to collect the results, or items() to
365 Initialize a new, empty configuration parser.
368 me._resolver = BulkResolver()
372 Parse configuration from a file F.
375 ## Initial parser state.
381 ## An unpleasant hack. Python makes it hard to capture a value in a
382 ## variable and examine it in a single action, and this is the best that
385 def match(rx): m[0] = rx.match(line); return m[0]
387 ## Commit a key's value when we've determined that there are no further
388 ## continuation lines.
390 if key is not None: sect._itemmap[key] = val.getvalue()
392 ## Work through all of the input lines.
396 if match(RX_COMMENT):
397 ## A comment or a blank line. Nothing doing. (This means that we
398 ## leave out blank lines which look like they might be continuation
403 elif match(RX_GRPHDR):
404 ## A section header. Flush out any previous value and set up the new
409 try: sect = me._sectmap[name]
410 except KeyError: sect = me._sectmap[name] = ConfigSection(name, me)
413 elif match(RX_ASSGN):
414 ## A new assignment. Flush out the old one, and set up to store this
418 raise ConfigSyntaxError(f.name, lno, 'no active section to update')
421 val = StringIO(); val.write(m[0].group(2))
424 ## A continuation line. Accumulate the value.
427 raise ConfigSyntaxError(f.name, lno, 'no config value to continue')
428 val.write('\n'); val.write(m[0].group(1))
433 raise ConfigSyntaxError(f.name, lno, 'incomprehensible line')
435 ## Don't forget to commit any final value material.
438 def section(me, name):
439 """Return a ConfigSection with the given NAME."""
440 try: return me._sectmap[name]
441 except KeyError: raise MissingSectionException(name)
444 """Yield the known sections."""
445 return me._sectmap.itervalues()
449 Works out all of the hostnames which need resolving and resolves them.
451 Until you call this, attempts to fetch configuration items which need to
452 resolve hostnames will fail!
454 for sec in me.sections():
455 for key in sec.items():
456 value = sec.get(key, resolvep = False)
457 for match in RX_RESOLVE.finditer(value):
458 me._resolver.prepare(match.group(1))
461 ###--------------------------------------------------------------------------
462 ### Command-line handling.
464 def inputiter(things):
466 Iterate over command-line arguments, returning corresponding open files.
468 If none were given, or one is `-', assume standard input; if one is a
469 directory, scan it for files other than backups; otherwise return the
474 if OS.isatty(stdin.fileno()):
475 M.die('no input given, and stdin is a terminal')
481 elif OS.path.isdir(thing):
482 for item in OS.listdir(thing):
483 if item.endswith('~') or item.endswith('#'):
485 name = OS.path.join(thing, item)
486 if not OS.path.isfile(name):
492 def parse_options(argv = argv):
494 Parse command-line options, returning a pair (OPTS, ARGS).
497 op = OptionParser(usage = '%prog [-c CDB] INPUT...',
498 version = '%%prog (tripe, version %s)' % VERSION)
499 op.add_option('-c', '--cdb', metavar = 'CDB',
500 dest = 'cdbfile', default = None,
501 help = 'Compile output into a CDB file.')
502 opts, args = op.parse_args(argv)
505 ###--------------------------------------------------------------------------
510 Read the configuration files and return the accumulated result.
512 We make sure that all hostnames have been properly resolved.
514 conf = MyConfigParser()
515 for f in inputiter(args):
520 def output(conf, cdb):
522 Output the configuration information CONF to the database CDB.
524 This is where the special `user' and `auto' database entries get set.
527 for sec in sorted(conf.sections(), key = lambda sec: sec.name):
528 if sec.name.startswith('@'):
530 elif sec.name.startswith('$'):
533 label = 'P%s' % sec.name
534 try: a = sec.get('auto')
535 except MissingKeyException: pass
537 if a in ('y', 'yes', 't', 'true', '1', 'on'): auto.append(sec.name)
538 try: u = sec.get('user')
539 except MissingKeyException: pass
540 else: cdb.add('U%s' % u)
541 url = M.URLEncode(semip = True)
542 for key in sorted(sec.items()):
543 if not key.startswith('@'):
544 url.encode(key, sec.get(key))
545 cdb.add(label, url.result)
546 cdb.add('%AUTO', ' '.join(auto))
551 opts, args = parse_options()
553 cdb = CDB.cdbmake(opts.cdbfile, opts.cdbfile + '.new')
556 conf = getconf(args[1:])
559 if __name__ == '__main__':
562 ###----- That's all, folks --------------------------------------------------